1. Field of the Invention
The present invention relates to a device for providing anti-reflux in a body fluid drainage and/or sampling system comprising at least one part providing a valve seat, and a valve element defining an outer contour formed from a sheet-shaped material blank, said valve element including at least one connecting portion and a flap portion and defining a longitudinal direction extending between the connecting portion and the flap portion, and retaining means for retaining the valve element with respect to the device, said retaining means being integral with the device.
2. Description of the Related Art
Devices for preventing backflow or reflux in systems for drainage and/or sampling of body fluids are well known in the art. Such devices, which either constitute or have the function of valves, may e.g. be positioned in a connector member connecting a urinary catheter with a urine drainage bag and prevent reflux of the collected urine to the catheter.
There are various designs of such devices. One type of valve which has proven efficient and which is at the same time of a simple structure is the flap or flutter type of valve. In such a valve, a relatively thin flap serves as a valve element and is connected with one or more parts of the device in such a way that the flap is able to flex or pivot between an open and a closed position. In the closed position, the flap abuts against a valve seat formed on any of the parts of the system. The flap thus allows for passage of fluid in one direction and seals against the valve seat when fluid pressure is exerted in the opposite direction.
The connection between the valve element and the other part or parts of the device may be carried out in different ways. One example is shown in GB patent application No. 2 313 430, in which a flap is formed as the inner portion of a hollow tubular structure forming a valve element. The flap of the valve element is connected integrally with a surrounding connecting portion at one point only and is thus separated from the connecting portion by a C-shaped slot. A simpler version of the same principle is disclosed in U.S. Pat. No. 3,529,599, in which the valve includes a disk-shaped valve element with a corresponding C-shaped slot. During manufacture of such a valve element, great care must be observed during provision of the slot, as the cut-out material produced may interfere with the manufacturing process and may, at worst, cause complete shutdown, just as any residual material on the cutting surface may affect the sealing properties of the valve. Furthermore, in order to obtain a correct seal, the valve seat of both of the above devices must extend radially inwards of the flap portion. Consequently, the overall dimensions of the anti-reflux device are necessarily relatively large in relation to the available inner dimensions of the tubes of the system.
U.S. Pat. No. 3,901,235 discloses an anti-reflux device positioned at the drip chamber of a body fluid collection bag, in which the valve element is relatively large and is sealed to the drip chamber around a major part of its periphery, leaving only the lower periphery free to pivot and allow for passage of fluid. However, as the flap portion thus only constitutes a small part of the valve element, there is a large amount of surplus material that does not take part in the actual function of the device. Furthermore, the sealing operation entails that the manufacture of the device becomes more complicated.
U.S. Pat. No. 3,968,925 discloses an anti-reflux valve located at the drip chamber of a fluid drainage bag, in which connecting portions of the valve element are formed as two radially extending ears protruding from the flap portion. The ears are received in retaining pockets formed under a separate retaining member in the form of a strip bonded to the drip chamber forming the valve seat. As the strip is only bonded to the drip chamber at selected portions, the valve element is slidably received in the pockets. In addition to the fact that such a slidable and thus immediately releasable connection is not desirable for all purposes, the manufacture and assembly of such a device is rendered expensive and cumbersome by the separate retaining member, its attachment to the drip chamber and the positioning of the valve element.
Furthermore, a commercially available device is known in which the valve element has the shape of a substantially cylindrical flap portion and a connecting portion, in which two apertures are formed for the accommodation of retaining means in the form of protrusions such as upstanding pins or the like. The valve elements including the apertures are usually formed by any suitable cutting operation, such as punching, of a blank of material. Due to the characteristics of the materials traditionally used in such valve elements and to the dimensions of the devices, difficulties may arise during manufacture of the valve elements. Such difficulties include that the cut-out or punched-out material in the form of free waste corresponding to the apertures may adhere to the valve elements due to static electricity generated by the handling of the material. In addition to the fact that the free waste may complicate the manufacturing process and the assembly of the device and render the valve leaking, it may have severe consequences if such free waste tears itself loose during use of the system and moves to other parts of the body fluid drainage and/or sampling system. Consequently, precautions in the form of an additional production step must be taken in order to secure that the free waste is removed during manufacture of the device.